As a result of elevated public concern about the safety of our water and food supplies and the ability of infectious diseases to rapidly spread through our globalized economies, pathogen detection is becoming increasingly important. Currently, the identification of most pathogens is achieved through the collection of a liquid sample. Common detection techniques involve either selectively culturing an organism or specifically identifying a marker of an organism. These techniques typically are not sufficiently sensitive to detect many pathogens that may be present at infectious levels. It may take hours (or days) to obtain the desired information. In addition, these techniques are often prohibitively expensive to implement on a continuous basis.
It may be more convenient, or even necessary, to analyze an air sample rather than a liquid sample. Environmental monitoring of the air is typically conducted in one of two ways, depending on whether the analyte is a biological or nonbiological analyte. For a nonbiological analyte, such as a radioisotope or a material such as asbestos, the sample is collected on a membrane, and the collected sample material is analyzed using the appropriate detection technology.
Membranes, however, have not been as useful in detecting airborne biological organisms. The continuous flow of dry air over a membrane desiccates the organism and makes it difficult to detect the organism using cell culture or other bioanalytical techniques. In addition, a major drawback in using membrane is fouling due to the protein adsorbing on the membrane surface. Instead, biological organisms typically are collected from the air using techniques such as the wetted wall cyclone separator. The airborne pathogens are collected by taking advantage of their inertia when as stream of air is forced to spin in a cyclonic manner, then entrained in a fluid for subsequent identification using flow cytometry, solid-phase immunoassay or cell culture. This method of detection is very expensive to operate on a continuous basis as it consumes tens of milliliters of reagent a minute to identify a pathogen at relevant concentrations.
A system that allows for more economical and effective detection of airborne pathogens is needed.